Seiko Presage SSA425 Open Heart vs Seiko Prospex "Turtle"
Seiko's timepiece meets Seiko's diver
Quick Verdict
The Seiko Presage SSA425 Open Heart ($250–$500) offers Seiko In-House Automatic precision in the tier below the Seiko Prospex "Turtle" ($500–$1,000). The Presage SSA425 Open Heart measures 40.5mm and is rated 50m (5 ATM). The Prospex "Turtle" counters with Made in Japan craftsmanship and 200m (20 ATM) Diver water resistance. Both are exceptional watches for their respective tiers.
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Specifications Compared
| Feature | Seiko Presage SSA425 Open Heart | Seiko Prospex "Turtle" |
|---|---|---|
| Price | $250–$500 | $500–$1,000 |
| Case Size | 40.5mm | 45mm |
| Movement | Automatic Caliber 4R38 | Automatic Caliber 4R36 |
| Caliber Type | Seiko In-House Automatic | In-House Automatic Manufacture |
| Power Reserve | 41 Hours | 41 Hours |
| Water Resistance | 50m (5 ATM) | 200m (20 ATM) Diver |
| Crystal | Hardlex Crystal | Sapphire Crystal |
| Case Material | Stainless Steel | Stainless Steel |
| Origin | Made in Japan | Made in Japan |
Category-by-Category Analysis
Design & Aesthetics
Seiko's design language vs Seiko's approach
The Seiko Presage SSA425 Open Heart features a Stainless Steel case at 40.5mm with Hardlex Crystal protection. The Seiko Prospex "Turtle" offers Stainless Steel construction at 45mm with Sapphire Crystal. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Automatic Caliber 4R38 vs Automatic Caliber 4R36
The Presage SSA425 Open Heart runs the Automatic Caliber 4R38 (Seiko In-House Automatic, 41 Hours power reserve) at 21,600 vph (3 Hz) frequency. The Prospex "Turtle" uses the Automatic Caliber 4R36 (In-House Automatic Manufacture, 41 Hours reserve) at 21,600 vph (3 Hz). Power reserves are closely matched.
Wearability & Fit
40.5mm vs 45mm — different wrist presence
At 40.5mm, the Presage SSA425 Open Heart wears more compactly on smaller wrists compared to the Prospex "Turtle" at 45mm. Water resistance differs: 50m (5 ATM) vs 200m (20 ATM) Diver.
Value & Cost of Ownership
Seiko sits in the lower tier
The Seiko Presage SSA425 Open Heart sits at $250–$500 and the Seiko Prospex "Turtle" at $500–$1,000. On the specs that outlast any price: the Presage SSA425 Open Heart uses Hardlex Crystal with 41 Hours, against Sapphire Crystal and 41 Hours on the Prospex "Turtle". Service intervals are typically 5-7 years for both.
Water Resistance
50m (5 ATM) vs 200m (20 ATM) Diver
The Presage SSA425 Open Heart is rated to 50m (5 ATM) while the Prospex "Turtle" handles 200m (20 ATM) Diver. The Prospex "Turtle" offers superior water resistance.
Our Verdict
Seiko
Presage SSA425 Open Heart
Choose the Seiko Presage SSA425 Open Heart if you prioritize Seiko In-House Automatic engineering, Made in Japan craftsmanship, and 50m (5 ATM) water resistance. At $250–$500, it delivers Automatic Caliber 4R38 with 41 Hours power reserve.
Check Price on AmazonSeiko
Prospex "Turtle"
Choose the Seiko Prospex "Turtle" if you value In-House Automatic Manufacture technology, Made in Japan heritage, and 45mm proportions. At $500–$1,000, the Automatic Caliber 4R36 with 41 Hours power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Seiko Presage SSA425 Open Heart and Seiko Prospex "Turtle" represent two distinct approaches to fine watchmaking — the Seiko bringing Made in Japan tradition while Seiko delivers Made in Japan engineering.
Frequently Asked Questions
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How This Page Was Made
Our comparisons are generated from a hand-maintained specification database and reviewed under our editorial standards. We use AI tools to assemble pages from that data. We don’t invent specs: every number traces back to the database, and when we correct an entry, the fix is applied site-wide. As an Amazon Associate, The Horologist earns from qualifying purchases.